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Let's suppose I have two network interfaces with one fe80:: address each one.

1: eth0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    link/ether 9e:b5:a0:04:24:d6 brd ff:ff:ff:ff:ff:ff
    inet6 fdeb:446c:912d:8da::/64 scope global noprefixroute 
       valid_lft forever preferred_lft forever
    inet6 fe80::dd83:eec8:1f40:2c14/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
1: eth1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    link/ether 7a:94:ff:78:76:8a brd ff:ff:ff:ff:ff:ff
    inet6 fdca:5d7ac:61ba:adfc::/64 scope global noprefixroute 
       valid_lft forever preferred_lft forever
    inet6 fe80::dd83:eec8:1f40:2c14/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

Can one fe80:: address communicate send/receive packets to/from the other fe80:: address?

phantomcraft
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    For clarity, the question is specifically about communication between link-local addresses on the same host? Idk what the use-case of that would be, it sounds a little odd. – Håkan Lindqvist Sep 10 '22 at 19:29
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    Each interface in the same host is in a different local network, so they could actually have the same link-local address. That is why you need to add the Zone ID when using link-local addresses, and traffic using link-local addresses is forbidden from being sent to a different network. – Ron Maupin Sep 10 '22 at 21:45
  • @HåkanLindqvist Yes, it is. I want to avoid any possibility of communication between two network interfaces because I'm writing a network namespace sandbox for using with Tor in transparent mode. – phantomcraft Sep 10 '22 at 21:53
  • FYI, your ULA addresses are using the zero address, which is allowed for IPv6, but that is the [Subnet-Router Anycast address](https://www.rfc-editor.org/rfc/rfc4291.html#section-2.6.1) for that network. – Ron Maupin Sep 10 '22 at 22:14

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